1. Field of the Invention
The present invention relates to quaternary ammonium compounds having muscarinic receptor antagonist or anticholinergic activity. The invention also relates to pharmaceutical compositions comprising these compounds, processes for preparing them and methods of use to treat pulmonary disorders.
2. State of the Art
Pulmonary or respiratory disorders, such as chronic obstructive pulmonary disease (COPD) and asthma, afflict many millions of people worldwide and such disorders are a leading cause of morbidity and mortality. Muscarinic receptor antagonists are known to provide bronchoprotective effects and therefore, such compounds are useful for treating respiratory disorders, such as COPD and asthma. When used to treat such disorders, muscarinic receptor antagonists are typically administered by inhalation. However, even when administered by inhalation, a significant amount of the muscarinic receptor antagonist is often absorbed into the systemic circulation resulting in systemic side effects, such as dry mouth, mydriasis and cardiovascular side effects. Additionally, many inhaled muscarinic receptor antagonists have a relatively short duration of action requiring that they be administered several times per day. Such a multiple-daily dosing regime is not only inconvenient but also creates a significant risk of inadequate treatment due to patient non-compliance with the required frequent dosing schedule.
Accordingly, a need exists for new muscarinic receptor antagonists. In particular, a need exists for muscarinic receptor antagonists having high potency, reduced systemic side effects when administered by inhalation, and a long duration of action thereby allowing for once-daily or even once-weekly dosing. In addition, a need exists for muscarinic receptor antagonists having high affinity for the receptor and a long receptor half life. Such compounds are expected to be particularly effective for treating pulmonary disorders, such as COPD and asthma, while reducing or eliminating side effects, such as dry-mouth and constipation.